why Glibc does not build with clang?

[Konstantin Serebryany <konstantin dot s dot serebryany at gmail dot com>]

Hello,

Today if you try to build Glibc with clang the compilation will fail
on a few dozen files.
The largest offenders are local functions [1] and VLAIS [2].
There are ~5 other easily fixable things, not worth discussing.

Would the Glibc team consider patches that remove local functions and VLAIS?
Is there any reason (technical/political/social/religious?) to keep
non-standard extensions
in Glibc, or this is just a lack of hands to do the cleanup?
(No intention to initiate a holly war, just want to know :)

Ability to build with clang may bring some new benefits to Glibc developers,
such as new warnings or some dynamic testing tools not available in GCC.
In particular I am interested in building Glibc with MemorySanitizer
to find bugs
in Glibc itself and to find more bugs in user code.

Thanks (and excuse me if this is some trivial FAQ),

--kcc

[1]
"error: function definition is not allowed here"

elf/dl-deps.c:159
elf/dl-load.c:2388
elf/dl-lookup.c:131
elf/dl-lookup.c:315
elf/do-rel.h:45
elf/get-dynamic-info.h:28
locale/weight.h:23  # included into other files.
locale/weightwc.h:23
nss/makedb.c:662
malloc/malloc.c:5045
crypt/md5-crypt.c:273
nptl/allocatestack.c:836
stdio-common/printf_fp.c:219
locale/programs/ld-ctype.c:2946
locale/programs/locale.c:802
locale/programs/locale.c:834
posix/regcomp.c:2787
posix/regcomp.c:2813
posix/regcomp.c:2882
posix/regcomp.c:2962
stdlib/rpmatch.c:36
sha256-crypt.c:346
sha512-crypt.c:345
sysdeps/x86_64/dl-machine.h:239 #included into other files

[2]
error: fields must have a constant size: 'variable length array in
structure'
extension will never be supported

nscd/nscd_helper.c:192
iconv/iconv_charmap.c:388
nscd/nscd.c:387
nscd/netgroupcache.c:148